1. Field of the Invention
The present invention relates to optical demodulators and particularly to a novel optical cathode ray tube providing a plurality of electron multiplier demodulation channels.
2. Description of the Prior Art
Recent developments in optical communication systems have been directed to the use of pulse code modulation in conjunction with ultra-short pulse generators such as mode-locked lasers. Such systems provide good signal-to-noise ratios but require very high speed detectors which have not been readily available. It has previously been proposed to use a fast scanning optical cathode ray tube in conjunction with a smoothing image dissector for detection and analysis of individual short duration light pulses. This device is more fully described in U.S. Pat. No. 3,814,979, issued June 4, 1974, and assigned to the same assignee as the instant application. Image dissectors having a plurality of output electron multiplier channels are also known, such as shown in U.S. Pat. No. 3,333,145, issued July 25, 1967. Another type of cathode ray tube used for switching a plurality of output channels is described in the publication "IRE Transactions on Electron Devices," ED-9, pp. 11-15, dated November 1962, by R. Kalibjian. This device used an electron gun with an electrical input signal and required a very wide bandwidth and variable frequency scan.